We report the results of a multi-year program to measure the vibration characteristics of the two Gemini telescopes. Measurements with fast-guiding wavefront sensors and networks of accelerometers show a correlation between image motion and optical vibrations induced mostly by instrument cryocoolers. We have mitigated the strongest vibrations by fast-guiding compensation and active cancellation of vibration sources.
The Gemini Multi-conjugate adaptive optics System (GeMS) at the Gemini South telescope in Cerro Pachon is the first sodium Laser Guide Star (LGS) adaptive optics (AO) system with multiple guide stars. It uses five LGSs and two deformable mirrors (DMs) to measure and compensate for distortions induced by atmospheric turbulence. After its 2012 commissioning phase, it is now transitioning into regular operations. Although GeMS has unique scientific capabilities, it remains a challenging instrument to maintain, operate and upgrade. In this paper, we summarize the latest news and results. First, we describe the engineering work done this past year, mostly during our last instrument shutdown in 2013 austral winter, covering many subsystems: an erroneous reconjugation of the Laser guide star wavefront sensor, the correction of focus field distortion for the natural guide star wavefront sensor and engineering changes dealing with our laser and its beam transfer optics. We also describe our revamped software, developed to integrate the instrument into the Gemini operational model, and the new optimization procedures aiming to reduce GeMS time overheads. Significant software improvements were achieved on the acquisition of natural guide stars by our natural guide star wavefront sensor, on the automation of tip-tilt and higher-order loop optimization, and on the tomographic non-common path aberration compensation. We then go through the current operational scheme and present the plan for the next years. We offered 38 nights in our last semester. We review the current system efficiency in term of raw performance, completed programs and time overheads. We also present our current efforts to merge GeMS into the Gemini base facility project, where night operations are all reliably driven from our La Serena headquarter, without the need for any spotter. Finally we present the plan for the future upgrades, mostly dedicated toward improving the performance and reliability of the system. Our first upgrade called NGS2, a project lead by the Australian National University, based a focal plane camera will replace the current low throughput natural guide wavefront sensor. On a longer term, we are also planning the (re-)integration of our third deformable mirror, lost during the early phase of commissioning. Early plans to improve the reliability of our laser will be presented.
The Gemini Planet Imager (GPI) is a facility extreme-AO high-contrast instrument – optimized solely for study of faint companions – on the Gemini telescope. It combines a high-order MEMS AO system (1493 active actuators), an apodized pupil Lyot coronagraph, a high-accuracy IR post-coronagraph wavefront sensor, and a near-infrared integral field spectrograph. GPI incorporates several other novel features such as ultra-high quality optics, a spatially-filtered wavefront sensor, and new calibration techniques. GPI had first light in November 2013. This paper presnets results of first-light and performance verification and optimization and shows early science results including extrasolar planet spectra and polarimetric detection of the HR4696A disk. GPI is now achieving contrasts approaching 10-6 at 0.5” in 30 minute exposures.
The Gemini Planet Imager (GPI) entered on-sky commissioning and had its first-light at the Gemini South (GS) telescope in November 2013. GPI is an extreme adaptive optics (XAO), high-contrast imager and integral-field spectrograph dedicated to the direct detection of hot exo-planets down to a Jupiter mass. The performance of the apodized pupil Lyot coronagraph depends critically upon the residual wavefront error (design goal of 60nmRMS with <5 mas RMS tip/tilt), and therefore is most sensitive to vibration (internal or external) of Gemini's instrument suite. Excess vibration can be mitigated by a variety of methods such as passive or active dampening at the instrument or telescope structure or Kalman filtering of specific frequencies with the AO control loop. Understanding the sources, magnitudes and impact of vibration is key to mitigation. This paper gives an overview of related investigations based on instrument data (GPI AO module) as well as external data from accelerometer sensors placed at different locations on the GS telescope structure. We report the status of related mitigation efforts, and present corresponding results.
The Gemini Planet Imager is an extreme AO instrument with an integral field spectrograph (IFS) operating in Y, J, H, and K bands. Both the Gemini telescope and the GPI instrument are very complex systems. Our goal is that the combined telescope and instrument system may be run by one observer operating the instrument, and one operator controlling the telescope and the acquisition of light to the instrument. This requires a smooth integration between the two systems and easily operated control interfaces. We discuss the definition of the software and hardware interfaces, their implementation and testing, and the integration of the instrument with the telescope environment.
An Atmospheric Dispersion Corrector (ADC) uses a double-prism arrangement to nullify the vertical chromatic
dispersion introduced by the atmosphere at non-zero zenith distances.
The ADC installed in the Gemini Planet Imager (GPI) was first tested in August 2012 while the instrument was
in the laboratory. GPI was installed at the Gemini South telescope in August 2013 and first light occurred later
that year on November 11th.
In this paper, we give an overview of the characterizations and performance of this ADC unit obtained in the
laboratory and on sky, as well as the structure of its control software.
The Gemini Multi-Conjugate Adaptive Optics System (GeMS) began its on-sky commissioning in January 2011.
The system provides high order wide field corrections using a constellation of five Laser Guide Stars. In December 2011, commissioning culminated in images with a FWHM of 80±2mas at 1.65 microns (H band) over an 87 x 87 arcsecond field of view. The first images have already demonstrated the scientific potential of GeMS, and after more than a year of commissioning GeMS is finally close to completion and ready for science. This paper presents a general status of the GeMS project and summarizes the achievements made during more than a year of commissioning. The characterization of GeMS performance is presented in a companion paper: “GeMS on-sky results”, Rigaut et al. Here we report on the sub-systems' performance, discuss current limitations and present proposed upgrades. The integration of GeMS into the observatory operational scheme is detailed. Finally, we present the plans for next year's operations with GeMS.
The Gemini Planet Imager is a next-generation instrument for the direct detection and characterization of young warm exoplanets, designed to be an order of magnitude more sensitive than existing facilities. It combines a 1700-actuator adaptive optics system, an apodized-pupil Lyot coronagraph, a precision interferometric infrared wavefront sensor, and a integral field spectrograph. All hardware and software subsystems are now complete and undergoing integration and test at UC Santa Cruz. We will present test results on each subsystem and the results of end-to-end testing. In laboratory testing, GPI has achieved a raw contrast (without post-processing) of 10-6 5σ at 0.4”, and with multiwavelength speckle suppression, 2x10-7 at the same separation.
The Gemini Multi-Conjugate Adaptive Optics System (GeMS} began its on-sky commissioning in January 20ll. The system provides high order wide-field corrections using a constellation of five Laser Guide Stars. In December 20ll, commissioning culminated in images with a FWHM of 80±2mas at 1.65 microns (H band} over an 87 x 87 arcsccond field of view. The first images have already demonstrated the scientific potential of GeMS, and after more than a year of commissioning GeMS is finally close to completion and ready for science. This paper presents a general status of the GeMS project and summarizes the achievements made during more than a year of commissioning. The characterization of GeMS performance is presented in a companion paper: "GeMS on-sky results" , R.igaut ct al. Here we report on the sub-systems' performance, discuss current limitations and present proposed upgrades. The integration of GeMS into the observatory operational scheme is detailed. Finally, we present the plans for next year's operations with GeMS.
GeMS, the Gemini Laser Guide Star Multi-Conjugate Adaptive Optics facility system, has seen first light in December 2011, and has already produced images with H band Strehl ratio in excess of 35% over fields of view of 85x85 arcsec, fulfilling the MCAO promise. In this paper, we report on these early results, analyze trends in performance, and concentrate on key or novel aspects of the system, like centroid gain estimation, on-sky non common path aberration estimation. We also present the first astrometric analysis, showing very encouraging results.
GeMS (the Gemini Multi-conjugated adaptive optics System) is a facility instrument for the Gemini-South
telescope. It will deliver a uniform, diffraction-limited image quality at near-infrared (NIR) wavelengths over an
extended FoV or more than 1 arcmin across. GeMS is a unique and challenging project from the technological
point of view and because of its control complexity. The system includes 5 laser guide stars, 3 natural guide
stars, 3 deformable mirrors optically conjugated at 0, 4.5 and 9km and 1 tip-tilt mirror. After 10 years since
the beginning of the project, GeMS is finally reaching a state in which all the subsystems have been received,
integrated and, in the large part, tested. In this paper, we report on the progress and current status of the
different sub-systems with a particular emphasis on the calibrations, control and optimization of the AO bench.
CANOPUS is the facility instrument for the Gemini Multi Conjugate Adaptive Optics System (GeMS) wherein all the
adaptive optics mechanisms and associated electronic are tightly packed. At an early stage in the pre-commissioning
phase Gemini undertook the redesign and implementation of its chilled Ethylene Glycol Water (EGW) cooling system to
remove the heat generated by the electronic hardware. The electronic boards associated with the Deformable Mirrors
(DM) represent the highest density heat yielding components in CANOPUS and they are also quite sensitive to
overheating. The limited size of the two electronic thermal enclosures (TE) requires the use of highly efficient heat
exchangers (HX) coupled with powerful yet compact DC fans.
A systematic approach to comply with all the various design requirements brought about a thorough and robust solution
that, in addition to the core elements (HXs and fan), makes use of features such as high performance vacuum insulated
panels, vibration mitigation elements and several environment sensors. This paper describes the design and
implementation of the solution in the lab prior to delivering CANOPUS for commissioning.
The tenth anniversary of Gemini Observatory operation provides a convenient reference point to reflect on the past,
present, and future of the instrumentation program. The Observatory will soon meet a significant milestone: the last
batch of instruments from the first three generations of instrumentation development will be commissioned by the end of
2011. This will represent a revolution for Gemini-South, which will have a suite of new or upgraded, state of the art
instruments. Included in this suite will be extreme and multi-conjugate adaptive optics systems, new infrared imagers
and multi-object spectrographs, and state of the art CCD detectors. The Observatory is on the cusp of a new era with the
fourth generation of instrumentation. While the past represented building a whole new observatory, the future represents
renewal and reinvestment, with plans for a new high-resolution optical spectrograph, new acquisition and guide units,
upgraded and refurbished instruments, and improved methods for developing Gemini instrumentation.
We present Canopus, the AO bench for Gemini's Multi Conjugate Adaptive Optics System (GEMS), a unique facility for
the Gemini South telescope located at Cerro Pachon in Chile. The MCAO system uses five laser beacons in conjunction
with different natural guide stars configurations. A deployable fold mirror located in the telescope Acquisition and
Guiding Unit (A&G) sends the telescope beam to the entrance of the bench. The beam is split within Canopus into three
main components: two sensing paths and the output corrected science beam. Light from the laser constellation (589nm)
is directed to five Shack-Hartman wave front sensors (E2V-39 CCDs read at 800Hz). Visible light from natural guide
stars is sent to three independent sensors arrays (SCPM AQ4C Avalanche Photodiodes modules in quad cell
arrangement) via optical fibers mounted on independent stages and a slow focus sensor (E2V-57 back-illuminated
CCD). The infrared corrected beam exits Canopus and goes to instrumentation for science. The Real Time Controller
(RTC) analyses wavefront signals and correct distortions using a fast tip-tilt mirror and three deformable mirrors
conjugated at different altitudes. The RTC also adjusts positioning of the laser beacon (Beam Transfer Optics fast
steering array), and handles miscellaneous offloads (M1 figure, M2 tip/tilt, LGS zoom and magnification corrections,
NGS probes adjustments etc.). Background optimizations run on a separate dedicated server to feed new parameters into
The Gemini Observatory presents the Helium Closed Cycle Cooling System that provides cooling capacity at cryogenic
temperatures for instruments and detectors. It is implemented by running three independent helium closed cycle cooling
circuits with several banks of compressors in parallel to continuously supply high purity helium gas to cryocoolers
located about 100-120 meters apart. This poster describes how the system has been implemented, the required helium
pressures and gas flow to reach cryogenic temperature, the performance it has achieved, the helium compressors and
cryocoolers in use and the level of vibration the cryocoolers produce in the telescope environment. The poster also
describes the new technology for cryocoolers that Gemini is considering in the development of new instruments.
The Gemini Multi-Conjugate Adaptive Optics project was launched in April 1999 to become the Gemini South
AO facility in Chile. The system includes 5 laser guide stars, 3 natural guide stars and 3 deformable mirrors optically
conjugated at 0, 4.5 and 9km to achieve near-uniform atmospheric compensation over a 1 arc minute square field of
Sub-contracted systems with vendors were started as early as October 2001 and were all delivered by July
2007, but for the 50W laser (due around September 2008). The in-house development began in January 2006, and is
expected to be completed by the end of 2008 to continue with integration and testing (I&T) on the telescope. The on-sky
commissioning phase is scheduled to start during the first half of 2009.
In this general overview, we will first describe the status of each subsystem with their major requirements, risk
areas and achieved performance. Next we will present our plan to complete the project by reviewing the remaining steps
through I&T and commissioning on the telescope, both during day-time and at night-time. Finally, we will summarize
some management activities like schedules, resources and conclude with some lessons learned.
We briefly describe the SOAR Optical Imager (SOI), the first light instrument for the 4.1m SOuthern Astronomical Research (SOAR) telescope now being commissioned on Cerro Pachón in the mountains of northern Chile. The SOI has a mini-mosaic of 2 2kx4k CCDs at its focal plane, a focal reducer camera, two filter cartridges, and a linear ADC. The instrument was designed to produce precision photometry and to fully exploit the expected superb image quality of the SOAR telescope over a 5.5x5.5 arcmin2 field with high throughput down to the atmospheric cut-off, and close reproduction of photometric pass-bands throughout 310-1050 nm. During early engineering runs in April 2004, we used the SOI to take images as part of the test program for the actively controlled primary mirror of the SOAR telescope, one of which we show in this paper. Taken just three months after the arrival of the optics in Chile, we show that the stellar images have the same diameter of 0.74" as the simultaneously measured seeing disk at the time of observation. We call our image "Engineering 1st Light" and in the near future expect to be able to produce images with diameters down to 0.3" in the R band over a 5.5' field during about 20% of the observing time, using the tip-tilt adaptive corrector we are implementing.
The Infrared Side Port Imager ISPI is a facility infrared imager for
the CTIO Blanco 4-meter telescope. ISPI has the following capabilities: 1-2.4 micron imaging with an 2K x 2K HgCdTe array, 0.3
arcsec/pixel sampling matched to typical f/8 IR image quality of ~0.6
arcsec and a 10.5 x 10.5 arcmin field of view. First light with ISPI
was obtained on September 24 2002, and since January 2003 ISPI has
been in operation as a common user instrument. In this paper we discuss operational aspects of ISPI, the behavior of the array and we report on the performance of ISPI during the first one and half year of operation.
The SOAR Optical Imager (SOI) is the commissioning instrument for the 4.2-m SOAR telescope, which is sited on Cerro Pachón, and due for first light in April 2003. It is being built at Cerro Tololo Inter-American Observatory, and is one of a suite of first-light instruments being provided by the four SOAR partners (NOAO, Brazil, University of North Carolina, Michigan State University). The instrument is designed to produce precision photometry and to fully exploit the expected superb image quality of the SOAR telescope, over a 6x6 arcmin field. Design goals include maintaining high throughput down to the atmospheric cut-off, and close reproduction of photometric passbands throughout 310-1050nm. The focal plane consists of a two-CCD mosaic of 2Kx4K Lincoln Labs CCDs, following an atmospheric dispersion corrector, focal reducer, and tip-tilt sensor. Control and data handling are within the LabVIEW-Linux environment used throughout the SOAR Project.
The new operations model for the CTIO Blanco 4-m telescope will use a small suite of fixed facility instruments for imaging and spectroscopy. The Infrared Side Port Imager, ISPI, provides the infrared imaging capability. We describe the optical, mechanical, electronic, and software components of the instrument. The optical design is a refractive camera-collimator system. The cryo-mechanical packaging integrates two LN2-cooled dewars into a compact, straightline unit to fit within space constraints at the bent Cassegrain telescope focus. A HAWAII 2 2048 x 2048 HgCdTe array is operated by an SDSU II array controller. Instrument control is implemented with ArcVIEW, a proprietary LabVIEW-based software package. First light on the telescope is planned for September 2002.